At 1940 UT (2:40 pm ET) on February 9, 2011 SDO will execute a Delta-H maneuver. This is a planned activity. Science data will be interrupted for about 30 minutes. The actual duration will be determined by the onboard software as it changes the reaction wheel speeds and fires the thrusters of the spacecraft to complete the maneuver. The goal is to adjust the reaction wheel speeds so we can maintain the pointing of the spacecraft over the next few months.
Here is a picture of a test thruster being fired on the ground in 2006 (we cannot see the actual thrusters on the spacecraft.) The thrusters should fire for up to 4 seconds.
UPDATE: The maneuver was completed using 66.6 gr of propellant with the thrusters firing for 4.05 sec. The satellite was pointing away from the Sun for about 15 min.
